Cloud synchronization refers to data synchronization between a cloud device and a server on a cloud platform, or data sharing between different devices of an individual on a cloud platform. The cloud synchronization provides a user with convenience and safety for mobile data backup, and can collect data stored in different devices by a user, so as to provide a platform which can be browsed and managed as a whole. Cloud synchronization of an image in a mobile device is to perform, on a server, a cloud storage backup on the image stored in the mobile device through a cloud synchronization solution. At present, in solutions provided by the prior art, there are below disadvantages: (1) resuming from breakpoint is not supported, i.e., if uploading of an image is interrupted due to disconnection of a network or exhaustion of a power supply of the device, the uploading of the image is desired to restart from scratch when synchronization is resumed, and it is not supported to continue the uploading from the position at which the file is interrupted previously; (2) detection of repeated synchronization of a same image is not supported, i.e., when a user has multiple devices and some of the devices have same photos, or another user has the same photos, the existing cloud synchronization solution will perform repeated uploading, resulting in a waste of resources.